#include<cstdio>

int n, nrp = 0;
int main()
{
	freopen("operatii.in", "r", stdin);
	freopen("operatii.out", "w", stdout);
	scanf("%d", &n);
	for (int i = 1, aux, lst = 0; i <= n; ++i, lst = aux)
	{
		scanf("%d", &aux);
		if (aux > lst)
			nrp += aux - lst;
	}
	printf("%d\n", nrp);
}